Power of Precision Heeling.
A dog can display very drastic behavioral changes once he has been taught how to walk in a precise heel position (next or behind the owner, no sniffing, no marking, turn and stop with the owner...etc). This drastic change can happen very quickly and almost magically.
A dog can go to the dog park for 3 hours daily and still jumps, whines, charges at people, and pulls like a train on the leash.
On the other hand, once the dog learns to walk in the heel position precisely, he will have a new outlook on his relationship with his owner--he knows what staying calm feels like first time for a change, and he also understands how relaxing it is to have a leader that he can follow. Heeling precisely also instills the important and often lacking concept of discipline and impulse control which is something a dog cannot learn from free play in the dog park.
Exercise is important but exercising at the dog park alone cannot improve the mindset of a dog in the same way. Letting a dog run free and do whatever he wants at the dog park constantly can cause an already unruly dog to become more "out of control" as he keeps practising being in a highly aroused state unchecked and be rewarded for it regularly.
A lot of owners have tried to put their dogs in doggy day care, adventure walks, off leash parks...but all they are doing is trying to wear their dogs out physically without teaching the dog to develop the mental capacity and discipline to stay calm and relax when needed.
Precision heeling addresses the mental aspect of the dog. It is a very powerful tool in modifying behavior quickly and effectively.
A dog that knows how to stay calm will behave himself first thing in the morning before any walk. He does not need to feel exhausted before he is obedient.